Open-type disposable diapers have been widely used for infants and the like. In such a disposable diaper, a back-side part and an abdominal-side part are attached with each other using tape fasteners, such as hook-and-loop fasteners. Generally, an open-type disposable diaper includes an inner part having an absorber which absorbs excreta from a wearer, a pair of side flaps which are continuously connected with both side end portions of the inner part, respectively. Tape fasteners are respectively attached to side end portions of the side flaps to project outward in the width direction of the disposable diaper.
Japanese Patent Application Publication No. 2000-126231 discloses an open-type disposable diaper with a side flap having a curved outer rim at a leg periphery portion so as to fit to the shape of the leg of a wearer.